<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        .father{
            width: 300px;
            height: 300px;
            background-color: beige;
        }
        .son{
            width: 100px;
            height: 100px;
            background-color: aqua;
        }
    </style>
</head>
<body>
    <div class="father">
        <div class="son"></div>
    </div>
    <script>
        //mouseover 和 mouseenter事件的区别:
        //1,mouseenter 不会产生冒泡事件
        //2,mouseover事件 会触发父盒子的事件 同时也会触发其中的子盒子的事件
        //3,mouseenter只会触发指定对象
        var father = document.querySelector('.father')
        father.addEventListener('mouseenter',function(){
            console.log('555')
        })
        
    </script>
</body>
</html>